1. Field of the Invention
The invention relates to a microscope with an objective turret that carries at least one objective and with a specimen holder for receiving a specimen.
2. Description of the Related Art
In actual practice, microscopes of the type under discussion here are known in the most differing designs. In the case of reflecting specimens, they operate according to the reflected light process, while transparent specimens are examined according to the transmitted light process.
Particularly in applications in the field of biology, medicine, etc., it is increasingly the case that xe2x80x9clivingxe2x80x9d objects are examined. Here it is often necessary to maintain the specimen under physiological conditions, including during the process of microscopic examination. This means that cell cultures, for example, during observation or measurement must be kept, e.g., at 37xc2x0 C., in order to assure the physiological conditions.
Adjusting the temperature of a specimen is problematic particularly in the case of microscopic examination at higher magnifications, specifically because there is only an extremely small working distance between the objective and the specimen. Even in the case of specimens that at first are successfully adjusted for temperature, the heat transfer over the microscope objective is so intense that the temperature directly at the point of examination, i.e., at the point nearest to the objective, is closer to the temperature of the objective than to the temperature around the slide or directly at the slide, as achieved by temperature adjustment. This works against microscopic examination or investigation of a temperature-adjusted specimen at high magnifications.
It is already known from actual practice to improve the described situation by directly heating the objective in use. To this end, heating sleeves have been positioned around the objective in order to bring the objective to the desired specimen temperature. The flow of heat over the microscope objective is thereby effectively prevented.
In actual practice, however, the solution known from the prior art for the indicated problem is extremely problematic, since the heating sleeve is positioned outside of and around the objective and when an objective turret is used the heating sleeve obstructs the adjacent positions of this objective when other objectives are used. Furthermore, application of the heating sleeve is associated with a considerable expense in time, which is particularly disruptive when the objective must be constantly changed to obtain different magnifications. The resulting expense is ultimately unacceptable. When the objective is changed, furthermore, it is not only necessary to remount the heating sleeve. The new objective must also be reheated, and here again much time is required. In any case, a rapid examination is not possible using the methods for heating individual objectives known from actual practice.
Finally, in actual practice it is also necessary to cool the specimens or slides. In this matter, the above remarks apply equally.
The invention is thus based on the problem of designing and elaborating a microscope of the indicated type, in such a way that, even when the objectives are constantly changed by means of the objective turret, the flow of heat over the microscope objective in momentary use is effectively avoided.
The microscope according to the invention solves the stated problem by an arrangement whereby all objectives carried by the objective turret are simultaneously adjusted for temperature by means of the objective turret.
The invention recognizes that the direct temperature-adjustment of only one objective makes no sense if the objective turret carries a plurality of objectives. The space that remains between the objectives is in any case insufficient to position the heating sleeve known from actual practice around the objective in use when the objective turret overall is outfitted with a plurality of objectives.
It is also recognized that during microscopic examination involving constantly changing magnifications it is necessary to simultaneously adjust the temperature of all the objectives on the turret, since otherwise an undesired heat flow from the specimen over the microscopic objective will always take place when a new objective is brought into working position by means of the turret.
Finally, it is recognized that this problem can be solved if all objectives carried by the turret are simultaneously adjusted for temperature by means of the turret. It is essential to the invention, therefore, that the objectives on the turret are not directly adjusted for temperaturexe2x80x94as in the prior artxe2x80x94but rather are indirectly adjusted, namely by means of heat conductance from the turret to the individual objective. External means applied to the objective for the purpose of adjusting the temperature of the objective are no longer necessary.
The temperature adjustment of the objective according to the invention can involve both heating and cooling, depending on whether the microscopic specimen is to be heated or cooled. In keeping with the specimen temperature, in any case, the objective can either be heated or cooled, the significant factor being that a constant temperature is maintained at the objective. To this end, a special control or regulating unit is also advantageously provided.
The temperature adjustment of the objective turret is realized in that a heating/cooling unit is positioned around the objective turret. This heating/cooling device is positioned outside of the operating area of the objective, so that the objective will not be obstructed. This heating/cooling device may advantageously take the form of a heating/cooling sleeve like that heretofore positioned around the individual objective.
In a particularly advantageous embodiment, the heating/cooling device is integrated into the objective turret. Here the heating/cooling device would not be visible from outside the objective turret and would not be obstructive. Only a line, or a pair of lines, to the objective turret would indicate that a special means was provided there.
In concrete terms, the heating/cooling device might comprise a line through which a flowing medium moves. The flowing medium might be a liquid or a gas. The flowing medium would be heated or cooled outside of the objective turret, while a thermostat for temperature control can be provided directly on the objective turret or inside it. Thus, achieving a preselected final temperature and maintaining that final temperature could be assured with simple means.
As an alternative, the heating/cooling device could comprise Peltier elements, which could cool as well as heat, depending on their polarity. It is also conceivable to provide only a heating device comprising heating resistors. Furthermore, the heating/cooling device could be electronically controlled, with the actual temperature on the objective turret being directly detected by a sensor device.
To avoid an undesired temperature line between the objective turret and the rest of the microscope, or the microscope stand, it is of particular advantage if the objective turret is thermally insulated from the microscope stand. This could be achieved, e.g., by producing the connection between the objective turret and the microscope stand out of a plastic that acts as a thermal insulator.
In a particularly advantageous embodiment that supplements the above indicated measures the platform serving to receive the specimen, or specimen holder, is also adjusted for temperature. To this end, a heating/cooling device could be integrated into the specimen holder; the heating/cooling device can be designed in exactly the same way as the heating/cooling device of the objective turret. For example, both heating/cooling devices could be provided with the same heating/cooling liquid, which in this case would be transported from a common reservoir for temperature-adjusted heating/cooling liquids. The same applies to further possibilities for heating and/or cooling. In similar fashion, it is possible to jointly regulate the heating/cooling device of both the objective turret and the specimen holder, so that the same temperature can be adjusted in both cases.